A fried egg sizzles in a pan as a somber actor tells you that this is a reputation of your brain on drugs. Most Americans are familiar with this macabre metaphor that was made famous by a series of commercials in the 1980s. The message is simple and vague, but the implication is that drugs damage your brain.
Throughout the late 20th century, marijuana was a particular source of panic because of its popularity and accessibility. Today, use of the drug hasn’t tapered off since the war on drugs in the ʼ80s and ʼ90s.
Millions of people use marijuana, and it’s the most commonly used illicit drug in the United States. As it dominates its spot as the most popular illegal drug, it’s also being decriminalized and even legalized for recreational use in states all over the country. The National Institute on Drug Abuse (NIDA) reports that marijuana use among high-schoolers declined slightly since the ʼ90s, but now teens perceive the drug as less dangerous.
But what are the effects of marijuana on the human brain? Is the fear of marijuana just an aftershock of the 20th-century drug panic or are teen brains going to be over easy? Learn more about marijuana and how it affects the brain.
How Marijuana Works on the Brain
Marijuana contains several psychoactive chemicals that affect the brain and body, including hundreds of chemical compounds and more than 60 cannabinoids, which are substances that act on cannabinoid receptors in the brain. The most potent of these chemicals is tetrahydrocannabinol (THC), a chemical that causes the relaxing and euphoric effects in marijuana.
THC attaches to cannabinoid receptors in the brain and in peripheral tissues. When these receptors are activated, they can alter your mood, change cognition, and increase your appetite. The effects of marijuana are dose-dependent, which means you may experience symptoms at high doses that you wouldn’t feel at lower doses and vice versa. For instance, larger doses of marijuana can impair your memory and cognitive functions while lower doses may only cause mild effects.
Marijuana is often taken to achieve a high, but some users claim that it promotes creativity. However, that may not be true. A study published in 2014 looked at the relationship between cannabis use and creative thinking. Participants performed a series of tasks that required “divergent thinking” and gave them a low dose of cannabis, a high dose, or a placebo.
People who used low doses didn’t have any notable increase in creativity as compared to the placebo group. People who used a high dose actually experienced impaired creativity. If you’re an artist, marijuana may not be the creativity enhancer you might want it to be.
Marijuana’s Short-Term Effects on the Brain
Acute effects of marijuana use can affect the brain and cognition in several ways. Marijuana’s effects can be extremely subjective. For instance, one person may feel energized while another feels sedated. This has to do with a variety of factors including the size of the dose, the size of the user, the specific strain of marijuana, and other variables. However, sedation is a common symptom of marijuana use and can even be hypnotic. Conversely, some strains may cause stimulating effects, especially ones that are high in THC and low in cannabidiol (CBD), which can have relaxing effects.
Marijuana can also cause physical and cognitive euphoria, which is a mental and emotional state in which you might feel a strong sense of well-being, elation, happiness, and contentment. However, cognitive euphoria in marijuana is said to be short-lived and mild in typical doses.
In some cases, especially in high doses, marijuana can cause anxiety and paranoia. However, some users report anxiety suppression. Marijuana can impair your ability to focus on a task and may cause you to lose focus, especially when you are surrounded by stimulating things.
Marijuana may also affect your emotions, enhancing any emotions you are feeling naturally. Happy people experience euphoria, nervous people experience paranoia, and when you find something amusing you may be more inclined toward bursts of laughter.
Cannabis can sometimes create psychedelic effects such as color enhancement and internal hallucinations (also called closed-eye hallucinations). These acute effects can last anywhere between 15 minutes and four hours.
Marijuana’s Long-Term Cognitive Effects on the Brain
Marijuana’s long-term effects on the brain are still poorly understood, although research has shed some light on the effects of consistent use. There is evidence for frequent marijuana use leading to lasting changes in the brain, affecting memory in cognition. For the most part, these effects can be reversed with abstinence, unless you start heavy use while your brain is still developing.
Some acute psychological effects of marijuana may last longer in some users than others. Studies suggest that THC can cause psychological symptoms and even psychosis in some people. In some cases, psychological disorders can be permanent. However, CBD has shown to counteract some of the psychosis-inducing effects of THC.
But illicit marijuana has intentionally low levels of CBD and high levels of THC. Illicit dealers create strains with those qualifications to produce more potent products that can be sold for higher prices and transported in smaller shipments.
Marijuana may also stunt important processes of brain development in adolescents, particularly a process called myelination. Myelin is a sheath of insulation that covers the axons of your nerve cells. This sheath helps to speed up signals sent throughout your nervous system. A healthy nervous system can send signals quickly throughout the body. One that doesn’t have enough myelin may suffer cognitive and even physical consequences.
While your brain is developing, especially during your teenage years, you go through a period of increased myelin growth. Alcohol, and to a lesser degree, marijuana can slow down this process. Heavy marijuana use during adolescence can lead to memory issues, cognitive impairment, and structural abnormalities in adolescent brains.
There is little evidence to definitively support the claim that marijuana is a gateway drug that causes people to be more likely to use harder drugs later. However, illicit drug users often start with marijuana. NIDA reports that studies in rats show that marijuana can lead to changes in the reward center of their brains. Adolescent rats showed a decreased reactivity to dopamine rewards later in life. This could mean that natural sources of reward can have a weaker impact on people who used marijuana as teens.
If the same phenomenon happens in people, adults with these effects may be more inclined to seek out more intense sources of reward like drugs or alcohol.